1. Field of the Invention
This invention relates to the creation of a clipped tail in a traveling web, such as the paper web produced on a papermaking machine. A tail clip is a device which cuts in a traveling web tail which severs, or clips, the tail laterally, so as to produce a free end of the traveling tail which can be lifted, deflected and directed into a desired location in the papermaking machinery for further processing of the web. When the clipped tail has been threaded through the entire papermaking machine, the tail can be widened to the desired full width of the web, to produce the paper product.
2. Description of the Prior Art
A clipped tail has been produced, after a fashion, by manually intercepting the traveling web, or tail, and tearing it to produce an end which is then directed by a metal wand, or a hand-held air pipe, into the downstream machinery. Methods and apparatus for mechanically producing or handling tails and clipped tails in a traveling paper web, such as produced on a papermaking machine, are also known. Some examples are shown and described in the following U.S. Pat. Nos. 4,904,344 (Peiffer); U.S. Pat. No. 4,136,808 (Reba); U.S. Pat. No. 3,625,813 (Eckelman); U.S. Pat. No. 4,671,151 (Rooney) U.S. Pat. No. 4,611,518 (Hildebrandt).
Heretofore, a clipped tail has been produced by positioning a pivotable doctor blade over a paper web tail as the tail is supported on the surface of a rotating roll. The doctor is pivoted against the paper web tail, to sever the tail by pinching the web between the doctor blade and the supporting surface beneath the web. This method works on lightweight paper grades, but is not reliable on heavier, paperboard grades.
Also known is the use of a high-pressure water jet for laterally cutting a traveling paper web tail as it travels while supported on the surface of a rotating roll. This procedure requires that the tail be removed from the roll surface by a blast of high pressure air, which is poor at directing the tail in a downstream direction.
Both of these tail clipping procedures produce a clipped tail, but are not adept at coordinating the production of the clipped tail with the transfer of the on-coming tail into downstream operations in the papermaking machine. The use of a directed stream of air, sometimes in association with a doctor or air pan arrangement is also known to convey a tail downstream.
Other problems relate to the lack of consistency in producing the clipped tail, due to the fact that the apparatus was positioned and loaded against the support surface, typically the surface of a rotating roll, by hand. Thus, where a doctor blade was positioned over the traveling tail and loaded against the tail by hand to clip the tail, frequently too great or too little pressure was applied by the doctor blade against the traveling tail, so as to either not sever the tail, or to crepe the newly severed tail, or to increase the wear of either or both the doctor blade or the surface of the rotating support roll. Further, some operators were more adept at effecting the clipped tail than others, and, regardless of what inefficiencies or problems occurred while producing the clipped tail, valuable production time was lost in threading the papermaking machine, so as to bring it up to full papermaking capacity. In addition, the close proximity of the operator to the machinery to effect the clipped tail and subsequent threading of the clipped tail represented a safety hazard.
The concepts of cross-cutting the paper tail with a high-pressure water jet, and engaging the paper web tail with a doctor blade have been combined previously, but such combinations have also heretofore been manually operated and controlled. Therefore, while additional reliability was made possible for producing the clipped tail, the total procedure took a relatively long time, and was still dependent on the skill of the individual operator to coordinate the separate tail clipping and tail directing functions, and sometimes took more than one operator. In a paper mill which runs 24 hours a day, such inefficiencies in the skill and number of operators and the apparatus resulted in inefficiencies in the transfer of the tail between sections of the papermaking machine, which, in turn, affected the overall economy of the paper production process.